Aion: Researches into the Phenomenology of the Self (Collected Works of C.G. Jung Vol.9 Part 2)
I regard these parallels as important because it is possible, through them, to relate so-called metaphysical concepts, which have lost their root connection with natural experience, to living, universal psychic processes, so that they can recover their true and original meaning.
In this way the connection is reestablished between the ego and projected contents now formulated as “meta- physical” ideas. Unfortunately, as already said, the fact that metaphysical ideas exist and are believed in does nothing to prove the actual existence of their content or of the object they refer to, although the coincidence of idea and reality in the form of a special psychic state, a state of grace, should not be deemed impossible, even if the subject cannot bring it about by an act of will.
Once metaphysical ideas have lost their capacity to recall and evoke the original experience they have not
only become useless but prove to be actual impediments on the road to wider development.
One clings to possessions that have once meant wealth; and the more ineﬀective, incomprehensible, and life- less they become the more obstinately people cling to them.
(Naturally it is only sterile ideas that they cling to; living ideas have content and riches enough, so there is no need to cling to them.)
Thus in the course of time the meaningful turns into the meaningless.
This is unfortunately the fate of metaphysical ideas. Carl Jung, Aion, Page 34.